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Search for "separation" in Full Text gives 868 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Configuration–packing synergy enabling integrated crystalline-state RTP and amorphous-state TADF
Beilstein J. Org. Chem. 2026, 22, 224–236, doi:10.3762/bjoc.22.16
- construct a twisted D–π–A molecular backbone. This molecular backbone achieves, on the one hand, frontier orbital spatial decoupling through donor–acceptor separation, reducing ΔEST and enabling TADF activation in amorphous environments. On the other hand, it retains the n→π* characteristics of the carbonyl
- 62.54°. These significant angles result in a distinctly twisted molecular framework, which plays a crucial role in spatially separating the donor (carbazole) and acceptor (phthalimide) segments of the molecule. This twisting and separation of the donor and acceptor parts of the molecule are critical for
- localized on the carbazole donor unit, while the lowest unoccupied molecular orbital (LUMO) is mainly concentrated on the phthalimide acceptor unit, as illustrated in Figure 1b and 1c. This significant separation of the HOMO and LUMO indicates a substantial frontier-orbital decoupling between the donor and
Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids
Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203
- greater charge separation in the excited state, which is more stabilized in polar solvents, typical of compounds that undergo an ICT upon excitation [86]. The use of EtOAc showed a hypochromic effect with a decrease in fluorescence emission. Similar results for chlorinated solvents (CH2Cl2, CHCl3) were
Recent advances in total synthesis of illisimonin A
Beilstein J. Org. Chem. 2025, 21, 2571–2583, doi:10.3762/bjoc.21.199
- product. They resolved racemic intermediate 27 by derivatization with (S)-1-(1-naphthyl)ethyl isocyanate, followed by separation of the resulting diastereomers via silica gel chromatography (Scheme 3). By converting diastereomer 32 to (−)-illisimonin A, the absolute configuration of the natural product
Ex-situ generation of gaseous nitriles in two-chamber glassware for facile haloacetimidate synthesis
Beilstein J. Org. Chem. 2025, 21, 2465–2469, doi:10.3762/bjoc.21.188
- were obtained when using purification by “dry column vacuum chromatography” [28], which allowed separation of anomers. In the seminal paper by Schmidt [29] dichloroacetimidates were also synthesized. They were described as too unreactive to be viable alternatives to the trichloro analogs. The synthesis
The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions
Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184
- of hexane and dried in open air. The resulting mixture of isomers was subjected to direct NMR analysis, without any additional purification or separation steps. Versatile compounds via cycloaddition reactions. a) Radar view of the physical properties of methyl laurate. b) Oral toxicity values of
Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications
Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179
- length. These modifications enabled large-amplitude shuttling motions and created sufficient spatial separation, ensuring the macrocycle resides exclusively at one recognition site at a time [55]. Dithienylethene Dithienylethene photoswitches undergo an electrocyclic reaction, forming a closed-ring
- for applications in anion transport, extraction, and separation technologies. Conclusion and Perspectives The development of photoswitchable rotaxanes has mainly focused on controlling the position and movement of the macrocycle along the axle. Consequently, the vast majority of systems reported to
A chiral LC–MS strategy for stereochemical assignment of natural products sharing a 3-methylpent-4-en-2-ol moiety in their terminal structures
Beilstein J. Org. Chem. 2025, 21, 2243–2249, doi:10.3762/bjoc.21.171
- –MS detection of the MPO-derived fragment and to achieve a separation of four candidate stereoisomers. To this end, methylation of commercially available methyl acetoacetate (2) and subsequent reduction of the ketone carbonyl group was carried out to prepare a mixture of four stereoisomers of methyl 3
- -hydroxy-2-methylbutanoate (3) [25][26]. We then explored LC–MS conditions for their separation. In our initial trial, the stereoisomeric mixture of 3 was successfully separated by preparative high performance liquid chromatography (HPLC) using a chiral column (data not shown). However, each stereoisomer
- complete separation of the stereoisomers was not achieved, the corresponding peaks exhibited improved resolution compared to those of 4 (Figure S2, Supporting Information File 1). To further enhance separation, the p-nitrobenzoyl (PNB) ester 6 was prepared (Scheme 1B). After repeated trials with several
Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates
Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169
- % reference for clearance calculations. HPLC–MS analysis. The semi-quantitative determination of test compounds was carried out using a Waters Xevo G2-XS QToF mass spectrometer equipped with an electrospray ionization (ESI) source operating in positive ion mode. Chromatographic separation was performed on a
C2 to C6 biobased carbonyl platforms for fine chemistry
Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165
- hydroxy group at the α-position of the carboxyl group (Scheme 10) [38]. Yang and his team reported a metal-free catalytic system for the conversion of LA to PA (Scheme 10a). The use of NaI as catalyst and PA itself as solvent allowed to simplify the product separation process, giving yields up to 99
- from homogeneous catalysts such as mineral acids, organic acids, metal salts (with high availability and low costs) to heterogeneous ones such as zeolites, metal oxides, sulfonated polymers, carbon-based solid acids. The latter allow to overcome the problems of separation encountered with homogeneous
Further elaboration of the stereodivergent approach to chaetominine-type alkaloids: synthesis of the reported structures of aspera chaetominines A and B and revised structure of aspera chaetominine B
Beilstein J. Org. Chem. 2025, 21, 2072–2081, doi:10.3762/bjoc.21.162
- aspera chaetominine B. Keywords: epoxidation; selective epimerization; stereodivergent synthesis; structural revision; tandem reaction; Introduction In contemporary organic chemistry, due to the widespread application of modern separation and analytical techniques, the structural elucidation and
α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions
Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157
- precipitation from non-polar solvents such as hexane and toluene did not lead to a complete separation of quinoxalinones 9 and Ph3PO. We attribute this to the ability of Ph3PO to form a strong hydrogen bond between the phosphoryl oxygen and a proton from the donor group of the second molecule [56][57][58], in
Measuring the stereogenic remoteness in non-central chirality: a stereocontrol connectivity index for asymmetric reactions
Beilstein J. Org. Chem. 2025, 21, 1995–2006, doi:10.3762/bjoc.21.155
- substituents. Intuitively, the intrinsic spatial separation among prochiral stereogenic elements, the reactive sites, and the stereochemical-defining substituents makes stereoinduction for non-central chirality using a chiral catalyst or reagent particularly challenging. However, a quantitative
Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation
Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149
- existence of inherent chirality for both MC1 and MC3, chiral resolutions using chiral high-performance liquid chromatography (HPLC) were performed. Due to insufficient solubility, MC3 failed in chiral separation via preparative chiral columns. Fortunately, two enantiomers of MC1 were successfully isolated
Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules
Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145
- cyclocondensation between these two components enabled by CPA catalysts yielded the inherently chiral DDDs 64 with good to high enantioselectivity (Scheme 18). While a number of reactions did not initially yield satisfactory enantioselectivity, facile phase separation during the workup process removed the less
- inherently chiral eight-membered azaheterocycles 72 with moderate to good enantioselectivity, along with the release of CO2 (Scheme 20). While the enantioselectivity using certain substrates was initially unsatisfactory, simple phase separation significantly enhanced the enantiopurity of the products by
Photoswitches beyond azobenzene: a beginner’s guide
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
- is symmetry-forbidden, which reflects in a low intensity of this band, while the Z-isomer is bent, giving rise to a higher intensity nπ* band [48]. The distorted nature of both Z- and E-isomers of diazocine makes the nπ* transition symmetry-allowed: as a consequence, the absorbance and the separation
- soluble in water. For C- and S-diazocine, the absorption band separation of the two isomers is lower in polar solvents, resulting in worse PSS. In particular, for the S-diazocine it was found that the E-chair conformer was bathochromically shifted with increasing polarity of the solvent until completely
- indigos [67]. In general, electron-donating substituents red-shift the absorption and decrease the thermal half-life, and vice versa for the electron-withdrawing ones. Phenyl rings with electron-withdrawing p-substituents allow a better fine-tuning of the spectral separation between the two isomers (thus
Unique halogen–π association detected in single crystals of C–N atropisomeric N-(2-halophenyl)quinolin-2-one derivatives and the thione analogue
Beilstein J. Org. Chem. 2025, 21, 1748–1756, doi:10.3762/bjoc.21.138
- ) observed in their single crystals. Results and Discussion Synthesis of quinoline-2-ones (thione), their enantiomer separation and rotational stability We focused on N-(2-halophenyl)quinolin-2-ones 1 and the thione analogue 2 as alternative substrates to verify chirality- and functional group-dependent
Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade
Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132
- back-pressure regulation within the continuous-flow reactor system becomes essential to maintain precise pressure control and prevent solvent vaporization. Continuous-flow nitration systems can be augmented with integrated process modules including in-line separation units (work-up zone), real-time
Chemical synthesis of glycan motifs from the antitumor agent PI-88 through an orthogonal one-pot glycosylation strategy
Beilstein J. Org. Chem. 2025, 21, 1587–1594, doi:10.3762/bjoc.21.122
- trials for post-resection hepatocellular carcinoma [26]. Interestingly, Ferro and co-workers revised the structure of PI-88 to I and II in 2017 via successful separation of oligosaccharide phosphate fractions by preparative ion-exchange chromatography (Scheme 1A) [27]. Besides the major components α(1→3
Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads
Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121
- donor–acceptor dyads based on perylene (Pe) and phenothiazine (PTZ), in which triphenylamine (TPA) units and a phenyl spacer were introduced to modulate donor strength and spatial separation. Among the series, Pe–PTZ(TPA)2 exhibits a distinct thermal equilibrium between the locally excited (LE) state of
- the LE state of the PTZ moiety. In contrast, Pe-Ph–PTZ(TPA)2, in which the donor–acceptor distance is increased by a phenyl spacer, does not show clear equilibrium behavior. These results underscore the crucial role of excited-state structural relaxation in tuning photoinduced charge separation, and
- demonstrate that precise electronic and geometric design can enable controllable excited-state behavior in orthogonal molecular systems. Keywords: charge transfer; electron transfer; molecular dyad; transient absorption; Introduction Photoinduced electron transfer and charge separation are fundamental
pH-Controlled isomerization kinetics of ortho-disubstituted benzamidines: E/Z isomerism and axial chirality
Beilstein J. Org. Chem. 2025, 21, 1568–1576, doi:10.3762/bjoc.21.120
- best of our knowledge, although the structural analysis of the E/Z isomerism of amidine [24][25] and the effect of the protonation of an amidine moiety on the rotational barrier of the C–N bond [26] have been studied, the separation of amidine E/Z isomers has not been reported yet. To verify our
- separation of the two peaks, HPLC analysis of each separated component showed single peaks, suggesting that the E and Z isomers of amidine 2 trifluoroacetate salt could be separated by standard RP-HPLC. The configuration of the amidine moiety of each component was characterized by NOE experiments (for
- protonated form calculated by the DFT method. Comparison of VT-NMR spectra of a) amidine 1 and b) its trifluoroacetate salt 1-H+ in DMSO-d6 (400 MHz). Separation and isolation of amidine E/Z isomers by RP-HPLC. The mobile phase contained CF3CO2H to protonate the amidine moiety. Kinetic analysis of the
Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones
Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113
- selectivity, and in all cases formation of insertion products of both types, i. e., thioaminals 9 and dithioacetales 10, was observed (see Table 1). Chromatographic separation enabled the isolation of pure compounds, and the more stable dithioacetals 10 formed the more polar fraction. The less polar fraction
- contained thioaminals 9, which underwent a slow isomerization in CDCl3 solution. Notably, in the case of products 9k and 10k, bearing a Ph group at N(1), after a successful chromatographic separation, the less stable 9k underwent isomerization in CDCl3 solution (at rt) and no registration of NMR spectra of
- in the series of products derived from 1c is slower (and reversible?), and therefore, corresponding products of both N- and S-insertion are side by side observed as components of the crude reaction mixtures and their ratio was always ca. 55:45. In the latter case, chromatographic separation of the
N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B
Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103
- funnel for 5 min to allow for proper separation of the constituent mixture between the aqueous and organic phases. Further partitioning of the aqueous phase with sec-butanol (300 mL × 3) yielded FB fraction (2.3 g) and FW fraction (1.4 g), respectively. The dichloromethane (FD) fraction (3.5 g) was
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
- ) can exhibit remarkably red-shifted absorption, even when incorporated into relatively small π-conjugated frameworks. Through careful molecular design – retaining the azulene-like electronic structure and promoting spatial separation of the HOMO and LUMO orbitals – it is possible to achieve
Synthetic approach to borrelidin fragments: focus on key intermediates
Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91
- impact the outcome. Subsequently, separation of 84 from 85 was explored using various lipases and an esterase. However, preliminary experiments with these enzymes did not yield satisfactory results. The focus then shifted to route B, utilizing methyl 2,4,6-trimethyloctanoate 88 as the starting material
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